Human FAM3C has been previously assigned to a subfamily of proteins that are characterized as cytokines (Zhu, et al., 2002, Genomics 80:144-150). The term cytokine was used initially to separate a group of immunomodulatory proteins, from other growth factors that modulate the proliferation and bioactivities of non-immune cells. Cytokine is a generic name for a diverse group of soluble proteins and peptides which act as humoral regulators which, either under normal or pathological conditions, modulate the functional activities of individual cells and tissues. Many cytokines show stimulating or inhibitory activities and may synergise or antagonize also the actions of other factors. A single cytokine may elicit reactions also under certain circumstances which are the reverse of those shown under other circumstances.
However, information presented herein, suggests that FAM3C and the novel variants described in this application bear structural similarity to certain enzymes, particularly glycosyltransferases. The biological roles of glycans includes those that rely on the structural and modulatory properties of glycans and those that rely on specific recognition of glycan structures by other molecules (generally receptor proteins or lectins). The second group can be divided into those involving recognition by endogenous receptors within the same organism and those resulting from recognition by exogenous agents, such as but not limited to, pathogen receptors and toxins.